Modded Tone Bender II

[voskarp]

Hello!

I have modified my homebuilt Tone Bender Mk II Pro with a 2PDT-switch (at the red arrows in the picture) to bypass the first transistor for a more Fuzz Face-ish (or TB 1,5) kind of fuzz.

But when using it with low attack it can get a bit dull, lacking hi range.

So my idea was to use a pot at the cap C1 (at the blue arrow in the picture) to get as much back as I wish.

Will this work, and if so what value should the pot have?

EDIT: I forgot to mention that C1 is 15nF.

[Mark Hammer]

Do yourself a favour and play with the value of R5.  Specifically, stick a 250k-500k variable resistance in series with it and see how increasing the total feedback resistance changes things.  You might want to place a 100-470pf cap in parallel with that added resistance to tame the highs and any unintended whining.  The higher feedback resistance value makes the sound "glitchier" and can achieve gated sounds, in conjunction with the Gain/Attack/Fuzz control.  Here's  the ZVex Woolly Mammoth's use of that:

[voskarp]

Thanks for the answer!

Excuse my ignorance, I'm not very experienced with audio electronics, but how will this effect the sound other than the possible gating that you describe, and obviously increased treble that I was after. I'm asking because I wouldn't want the sound to change too much from that I get by bypassing the first transistor (except having possibility to increase hi frequencies).

As I understand it, cutting of the cap C1 wont have much effect on the sound, or? I got the idea for this modification because the TB-1,5/FF doesn't have that cap.

[voskarp]

Wouldn't I rather ad something like the EQ-thing from the Wooly Mammoth circuit?

[voskarp]

Oooh Kaay then...

[Derringer]

What Mark's saying is that by adjusting the feedback resistor's value, you'll alter the character of the circuit. With greater than 100K, you'll have less negative feedback which in turn may brighten things up for you.

Otherwise though, and my experience with fuzz faces is minimal ... they never did "it" for me, realize that by having the attack low, you're setting the circuit to specifically not have a lot of harmonic content (i.e. "highs). To achieve greater highs, you may have to cut the lows, and that would include reducing values for c2 and/or c3. You may find a happy balance in both modes, TB/FF, with smaller value C2 and/or C3 ... maybe not.

Another thing to consider, when you have your 2pdt in bypass mode - bypassing Q1 that is, I'm assuming r2 is still connected? if it is, that's going to attenuate your signal and even greater amount than a straight forward FF and would also result in less highs.

I'd only leave C1 in place if you can hear any audible difference with it in circuit. I think it's only there to prevent HF oscillation/radio frequencies, etc ... and you may not have that problem. It is making a low pass RC filter with whatever comes befre it so it is trimming some highs ... but so is the tone pot in your guitar and that's adjustable.

[voskarp]

I see, thanks for explaining and expanding.

Now I have some paths to explore, and not just cutting and soldering blindly.

[pinkjimiphoton]

instead of boosting treble, cut bass. its easier. a simple hi pass filter will work. you can google them.

one of my fav tricks is in the build doc for guitarpcb.com's dsotm fuzz.... it uses a cool combo that effectively cuts bass with one pot, cuts treble with the other.   you gotta register to view the project i think.

you usually will find things easier to cut than boost. less bass = more mids and treble, less treble = more mids n bass.

[voskarp]

Thanks for the suggestion!

I read up on this circuit and there's a variety called Marshall Superfuzz which has a fatter, bassier tone. The only difference is R1 is 10K instead of stock 100K, C2 and C6 are 10u instead of 4.7u.

If you change those in the other direction you'd get less bass, or..?

Especially the R1 is easily exchanged for a 250K pot, so you can change it according to taste.

[Electric Warrior]

Thanks for the suggestion!

I read up on this circuit and there's a variety called Marshall Superfuzz which has a fatter, bassier tone. The only difference is R1 is 10K instead of stock 100K, C2 and C6 are 10u instead of 4.7u.

If you change those in the other direction you'd get less bass, or..?

Especially the R1 is easily exchanged for a 250K pot, so you can change it according to taste.

The larger electrolytics hardly make any difference from what I can tell and 10k on Q1B is one of the stock values. Also, the Supa Fuzzes with the 10µFs don't have the 0.01µF at the input, so they actually have a little more high end.

These came with either 10k on Q1B and 47k on Q2C or 100k for both. The 10k variant needs more leakage to bias correctly. Biasing on Q3c is not necessary as its voltage depends on Q2. If you set Q2 right, Q3 will be in the right ballpark as well.

[voskarp]

Aha! Scrap that one then.

Looks like the simple bas/low mids attenuating thing wins.

[voskarp]

I find after listening to some youtube demos that the pinch thing might have to much effect besides the EQ I’m after...

What it does I kind of get in the Buzzaround if I’m after that kind of thing.